Process of deliming hides



UNITED STATES PATENT OFFICE.

WALLACE SAVAGE, OF NEW YQR-K, N. Y.

PROCESS OF DELIMING EIDES.

No Drawing.

To all whom it may concern:

Be it known that l, VVALLACE Samoa, a citizen of the United States. residing at New York, in the county of New York and State of New York, have invented certain newand useful Improvements in Processes of Deliming Hides, of which the following is a specification.

This invention relates to processes known in the tanning art as deliming hides and has particular reference to a novel process of deliming hides, by means of a base adsorbing or base exchanging earth, such for example, as fullers earth, zeolites or permutite.

In depilating hides, after they have been soaked and thoroughly cleaned, they are immersed in baths which dissolve. decompose or destroy the cellular matter in,,which the hair is rooted. Various methods for the solution, softening or disintegration of the matter which binds the epidermis and hair to the true skin, or that portion of the skin which enters into the formation of leather, are practised by tanners. Of these [)IQFQSSQS liming or thetreatment of the hides with a solution of calcium hydroxid or barium hydroXid, or other alkaline solution of alkaline earth metal compounds, is believed to be the oldest and at the present time, is very extensively used.

In attempting to remove the lime or similar depilating material or compounds thereof from the depilated hides, it has been found that no amount of scraping and rins- .ing will effect the required removal, a portion of such depilating agent being retained in the pores of the skin, combined as it is believed, with some of the decomposed tissue and with the grease and fat of the hides. These compounds if not decomposed or altered and removed not only obstruct the impregnation of the tanning liquor into the gelatin and fibrin of the hides, but also unpart a rigidity to the leather which prevents its satisfactory use where a soft, tough and pliable leather is required.

Numerous processes are employed to effect the deliming of depilated hides. The method known as hating is performed by macerating the dung of pigeons, dogs, etc, in water and immersing the scraped and depilated hides therein for a certain period, when the compounds resulting from the use of depilating agents of the character referred to are rendered soluble and are re- Specification of Letters Patent. Patented June 21, 15-221 Application filed April 26, 1919. Serial No. 292,936.

moved. It is believed that ammonium salts formed from the animal excrements producev soluble alkaline earth metal salts and ammonia, thereby making possible the complete removal of such compounds by elutriation with water. Other solvent methods have been used with considerable success such as. the use of dilute hydrochloric acid, saccharine solutions, lactic acid, fermenting llquors, etc.

New, I have found that earths having an attraction or affinity for bases as, for example, earths or clays having the power of adsorbing or of fixing by basic exchange alkaline earth bases, will removethe zompounds produced by the use of depilating agents of the character referred to from depilated hides in a more efficient and economical manner than heretofore has been practised in the leather making art.

For removing compounds of the character referred to, I have found that fuller-s earth, preferably that from central Georgia is most satisfactory. Dr. Charles L. Parsons, in Bureau of Mines Bulletin No. 71, page 82, gives the base fixing power of a score of well known deposits of fullers earth which show the general run of numerous mines. However, different parts of the same mine frequently yield earths which vary and proper selection should be made in mining the, earths. In addition to its property of adsorbing bases, fullers earth has the property of adsorbing greases for which purpose it has been used in fulling wool, This is an advantage as the hides treated with fullers earth and after being dried with it thereon, have an increased power of adsorbing tanning liquors.

Another type of earths called zeolites have properties which render them adapted for use in the practice of my invention but zeolites are not so desirable since they do not adsorb the impurities but exchange bases with the colloidal lime soaps to produce soluble soda or potash soaps, and considerable washing has to be performed in order to entirely remove these compounds from the cells of the treated skins. Permutite may be used but I have obtained the most satisfactory results with fullers earth and its use is preferred.

My preferred practice is to treat the depilated and limed hides with a, water paste made of fullers earth produced by adding from 100 to 200 or more, parts by weight of fullers earth is readily removed.

water to 10 parts by weight of fullers earth, according to the thinness of the paste desired. The hide is coated by either immersion in the paste or by brushing, flushing or otherwise applying the slurry or fullers earth onto the surface of the hides. A suflicient coat is applied to furnish the earth required to adsorb the compounds produced by the action of the depilating agent from the hide and the hide allowed to dry. After the hide has dried the limy and greasy spent Drying is not necessary and should itonly be desired to remove the compounds produced by the depilating agent, the use of a sufiicient quantity of fullers earth will extract the compounds referred to and it can then be washed off without the intermediate drying V operation. I

I have found that thoroughly satisfactory results may be obtained in the removal oi the compounds produced by the depilating agent by the employment of the fullers earth paste in the proportions of from onefourth per cent. to one per cent. of the weight of the hides. It will be understood, however, that larger amounts will react more rapidly and that the quantity of the earth to be employed will ordinarily be determined from considerations of economy.

In making use of zeolitic earths or permutite, I prefer to add from ten to twentyfive per cent more of the slurry 'or paste than I employ when the fullers earth is used.

In some cases my procedure may be modified as follows: The'hides can be initially treated in a superficial and rapid way by the use of only a sufficient amount of r'ul'lers earth to adsorb the bulk of the compounds to be removed and then treated bysome other deliming agent to remove the remaining portion of such compounds, preferably using lactic acid. In this way, the 7 procedure and proportions of reagents may be widely varied and that known chemical equivalents of the materials used may be employed,all without departure from the spirit of my invention or the scope of the subjoined claims. 7 r

Having described my invention, I claim:

1. The herein described process of cleliming .depilated hides which consists in subjecting them to the action of a base adsorbing earth paste, allowing the paste to remain in contact with the hides until impurities are removed, and then removing the limed p'aste from the hides.

2. The herein described process of deliming depilated hides which consists in subjecting them to the action of a fullers earth paste, allowing the paste to remain in contact with the hidesuntil impurities are removechand then removing the limed-paste from the hides. I

In testimony whereof Iaflix my signature in presence of two witnesses.

WALLACE sAvAen 'I/Vitnesses ALAN G. WiKorF, A. W. ALLEN. 

